The present invention generally relates to turbine flowmeters, and more particularly to a turbine flowmeter in which a turbine rotor is supported by a mechanical bearing when the flow quantity of a fluid is low and a dynamic pressure bearing acts on the turbine rotor when the flow quantity of the fluid is high, whereby the measuring range of the flow quantity is widened.
Conventionally, a turbine flowmeter is used to measure the flow quantity of gases which are used in homes or in industries. As methods of supporting the turbine rotor in such a turbine flowmeter, there are methods of using (i) a ball bearing, (ii) a pivot bearing, (iii) a slide bearing and the like. The above mentioned methods, however, have disadvantages in that the method (i) requires frequent maintenance, the method (ii) introduces a large wear due to friction when the rotor is rotated at a high speed, and the method (iii) introduces a large frictional resistance with respect to the rotation of the rotor.
Further, in the conventional turbine flowmeter which employs one of the above mentioned supporting methods, the measuring accuracy becomes poor in the low flow quantity region and/or the high flow quantity region, whereby the effective measuring range is narrowed.